Method and apparatus for redirection of server external hyper-link references

ABSTRACT

A message is provided to a tracking server system in response to a client system referencing a predetermined resource locator that corresponds to a resource external to the tracking server system. The tracking server system indirectly provides for the client system to have an informational element selectable by the client system, where the informational element is graphically identified on the client system with informational content obtainable from a content server system through use of a content resource locator. The informational element includes a tracking resource locator, referencing the tracking server system, and data identifying the informational element. The selection of the informational element causes the client system to use the tracking resource locator to provide the data to the tracking server system and to use the content resource locator to obtain the informational content from the content server system.

This application is a Continuation of application Ser. No. 13/340,565,filed on Dec. 29, 2011, which is a Continuation of application Ser. No.12/660,423, filed on Feb. 26, 2010, which is a Continuation ofapplication Ser. No. 11/031,100, filed on Jan. 6, 2005, now U.S. Pat.No. 7,702,752, which is a Continuation of application Ser. No.10/190,341, filed on Jul. 3, 2002, now U.S. Pat. No. 6,859,833, whichapplication is a Continuation of application Ser. No. 09/655,999, filedon Jun. 6, 2000, now U.S. Pat. No. 6,466,966, which application is aContinuation of application Ser. No. 09/071,674, filed on May 1, 1998,now U.S. Pat. No. 6,189,030, which is a Continuation-In-Part ofapplication Ser. No. 08/999,727, filed on Dec. 23, 1997, now U.S. Pat.No. 5,870,546, which is a Continuation of application Ser. No.08/604,468, filed on Feb. 21, 1996, now U.S. Pat. No. 5,751,956, whichapplications are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally related to the control of networkinformation server systems supporting World Wide Web based data pagesand, in particular, to a server system and process for efficientlyredirecting external server hyper-link references for purposes ofcontrolling, moderating, and accounting for such references.

2. Description of the Related Art

The recent substantial growth and use of the internationally connectednetwork generally known as the Internet has largely been due towidespread support of the hypertext transfer protocol (HTTP). Thisprotocol permits client systems connected through Internet ServiceProviders (ISPs) to access independent and geographically scatteredserver systems also connected to the Internet. Client side browsers,such as Netscape Mozilla® and Navigator® (Netscape CommunicationsCorp.), Microsoft Internet Explorer® and NCSA Mosaic™, provide efficientgraphical user interface based client applications that implement theclient side portion of the HTTP protocol.

Server side application programs, generically referred to as HTTPdservers, implement the server side portion of the HTTP protocol. HTTPserver applications are available both commercially, from companies suchas Netscape, and as copyrighted freeware available in source code formfrom NCSA.

The distributed system of communication and information transfer madepossible by the HTTP protocol is commonly known as the World Wide Web(WWW or W3) or as simply “the Web.” From a client side user interfaceperspective, a system of uniform resource locators (URLs) is used todirect the operation of a web browser in establishing atomictransactional communication sessions with designated web server computersystems. In general, each URL is of the basic form:

-   -   http://<server_name>.<sub-domain.top_level-domain>/<path>

The server_name is typically “www” and the sub_domain.top-level_domainis a standard Internet domain reference. The path is an optionaladditional URL qualifier.

Specification by user selection of a URL on the client side results in atransaction being established in which the client sends the server anHTTP message referencing a default or explicitly named data fileconstructed in accordance with the hypertext mark up language (HTML).This data file or web page is returned in one or more response phaseHTTP messages by the server, generally for display by the clientbrowser. Additional embedded image references may be identified in thereturned web page resulting in the client browser initiating subsequentHTML transactions to retrieve typically embedded graphics files. A fullyreconstructed web page image is then presented by the browser throughthe browser's graphical user interface.

Due to the completely distributed client/server architecture of the Web,as made possible by the URL system further supported by the existingInternet name resolution services and routing conventions, HTTP serverscan be independently established with little difficulty. Consequently,the Web has no centrally or even regionally enforced organization otherthan loosely by name of the top level domain. Searching for informationor other resources provided by individual HTTP servers is thereforeproblematic almost by definition. Because of the time, cost andcomplexity of assembling comprehensive, yet efficiently searchabledatabases of web information and resources, commercial Internet BusinessServices (IBS) have been established to provide typically fee based oradvertising revenue supported search engine services that operateagainst compilations of the information and resources available via theWeb correlated to source URLs. Access to such search engines is usuallyprovided through server local web pages served by the Internet BusinessServices. The results of a search are served in the form of local webpages with appropriate embedded remote or hyper-linked URLs dynamicallyconstructed by the server of the Internet Business Service.

Because of the opportunity presented by the likely repeated clientaccess and retrieval of search engine and search result web pages,providers of other Internet based services have begun to actively placeadvertisements on these web pages. As is typical in advertising mediums,the frequency of display of an advertisement generally defines thecompensation paid to the advertisement publisher. Thus, the number oftimes that an advertisement is simply transferred to a client browserprovides an indication of how effectively the advertisement is beingpublished. A more direct measure of the effectiveness of a particularadvertisement on a particular web page is the number of times a clientweb browser chooses to actively pursue the URL represented by theadvertisement. Thus, there is a need to be able to track informationobtainable from a client browser when a hyper-linked advertiser's URL isselected.

The difficulty in obtaining direct reference information arises from thefact that a web page with an embedded advertisement and correspondingremote URL is served in its entirety to the client browser upon firstreference to the web page. The selection of a particular advertiser'sURL is then by definition performed through an independent transactiondirected to the HTTPd server associated with the advertiser. Since theadvertiser publishing HTTPd server is not part of this subsequenttransaction, the publishing server is conventionally incapable oftracking client browser hyper-links actually executed to an advertiser'sURL or any other URLs embedded in a web page previously served to theclient browser.

Simple web page access counters are relatively well known and usedthroughout the Web. These access counters are based on a common gatewayinterface (CGI) facility supported by modern HTTPd server systems. TheCGI facility permits generally small programs, at least typically interms of function, to be executed by a server in response to a clientURL request. That is, the HTML web page definition provides for theembedding of a specific HTML reference that will specify execution of aserver side CGI program as part of the process of the web browserreconstructing an image of a served web page. Such a HTML reference istypically of the form:

-   -   <img src=“http://www.target.com/cgi-bin/count.cgi”>

Thus, a counter value incremented with each discrete execution of theCGI program (count.cgi) dynamically provides part of the displayableimage of the reconstructed web page. The time, remote client requester,client domain, client browser type and other information that may beknown through the operation of the HTTP protocol may be logged as partof the CGI program's function. Consequently, a reasonable manner ofaccounting and auditing for certain web page accesses exists.

Access counters, however, fundamentally log only server local web pageaccesses. The client browser to the CGI program is evaluated by theclient in connection with the initial serving of the web page to theclient browser. The initial serving of the web page to the clientbrowser can be connected, but any subsequent selection of a URL thatprovides a hyper-link reference to an external server is not observedand therefore is not counted by a CGI program based access counter.Other limitations of access counters arise from the fact that theimplementing CGI program is an independently loadable executable. TheCGI program must be discretely loaded and executed by the servercomputer system in response to each URL reference to the CGI program.The repeated program loading and execution overhead, though potentiallysmall for each individual invocation of the CGI program, can represent asignificant if not substantial load to the sever computer system. Thefrequent execution of CGI programs is commonly associated with adegradation of the effective average access time of the HTTPd server inresponding to client URL requests. Since an Internet Business Serviceproviding access to a search engine logs millions of requests each day,even small reductions in the efficiency of serving web pages canseriously degrade the cost efficiency of the Internet Business Service.As of December, 1995, Infoseek Corporation, in particular, handles anaverage of five million retrievals a day.

The execution overhead associated with CGI programs is often rathersignificant. Many CGI programs are implemented at least in part throughthe use of an interpreted language such as Perl or TCL. Consequently, asubstantial processing overhead is involved in multiple mass storagetransfers to load both the interpreter and CGI program scripts, toprocess the scripts through the execution of the interpreter, and thenactually log whatever useful data is generated, typically to persistentmass storage. Finally, the interpreter and/or CGI program may have to beunloaded.

In addition, external CGI programs present a significant problem interms of maintenance, including initial and ongoing server configurationand control, and security in the context of a busy server system.Individual CGI programs will likely be needed for each independent webpage in order to separately identify web page service counts.Alternatively, a CGI program can be made sufficiently complex to be ableto distinguish the precise manner in which the program is called so asto identify a particular web page and log an appropriately distinctiveaccess count. Maintenance of such CGI programs on a server system wherelarge numbers of page accesses are being separately counted is nontrivial.

Further, the existence of external programs, particularly of scriptsthat are interpreted dynamically, represents a potential securityproblem. In particular, the access and execute permissions ofinterpreted scripts must be carefully managed and monitored to preventany unauthorized script from being executed that could, in turn,compromise the integrity of the data being collected if not thefundamental integrity of the server computer system itself.Consequently, known access counters provide no solution directly in fullor in part to the need to account or audit URL references to externalservers based on hyper-links from previously served web pages.

The HTTP protocol itself provides for a basic server based system of URLredirection for servers and clients supporting the 1.5 or later versionsof the HTTP protocol. A configuration file associated with an HTTPserver (typically srm.conf) can specify a redirect directive thateffectively maps a server local directory URL reference to an externalURL reference through the use of a configuration directive of the form:

-   -   Redirect /dir1 http://newserver.widget.com/dir1

When a Version 1.5 or later HTTP server receives a URL reference to alocal directory (/dir1) that is specified as above for redirection, aredirect message is returned to the client browser including a newlocation in the form of an URL (http://newserver.widget.com/dir1). Thisredirect URL is then used by the client browser as the basis for aconventional client URL request.

This existing server based redirection function is insufficient tosupport external server access tracking since, in its usual form, theredirection is of the entire directory hierarchy that shares a commonredirected base directory. Even in the most restricted form, theredirection is performed on a per directory reference basis. Thus, everyaccess to the directory, independent of the particular web page orgraphics image or CGI program that is the specific object of an accessrequest is nonetheless discretely redirected without distinction. Anypotential use of the existing server redirect function is thereforeexceedingly constrained if not practically prohibited by the HTTPprotocol defined operation of the redirect directive.

Furthermore, the redirect directive capability of the HTTP protocolserver does not provide for the execution of a CGI program or otherexecutable coincident with the performance of the redirection therebyessentially precluding any action to capture information related to theredirect URL request. In addition, the complexity of the resourceconfiguration file necessary to specify redirection down to a perdirectory configuration again raises significant configuration,maintenance and, to a lesser degree, security issues. Thus, serverredirection does not possess even the basic capabilities necessary tosupport external URL hyper-link reference auditing or accounting.

Finally, a form of redirection might be accomplished though theutilization of a relatively complex CGI program. Such a redirection CGIprogram would likely need to perform some form of alternate resourceidentification as necessary to identify a redirection target URL.Assuming that a unique target URL can be identified, a redirectionmessage can then be returned to a client from the CGI program throughthe HTTP server as necessary to provide a redirection URL to the clientbrowser.

Unfortunately, any such CGI program would embody all of thedisadvantages associated with even the simplest access counter programs.Not only would problems of execution load and latency, as well asconfiguration, maintenance and security remain, but such an approach toproviding redirection is inherently vulnerable to access spoofing.Access spoofing is a problem particular to CGI programs arising from thefact that the HTML reference to the CGI program may be issued withoutrelation to any particular web page. Consequently, any CGI programimplementing an access counter or other auditing or accounting datacollecting program can produce an artificially inflated access countfrom repeated reference to the CGI program HTML statement outside andindependent of a proper web page. Access spoofing inherently underminesthe apparent if not actual integrity of any data gathered by a CGIprogram. Since, at minimum, the ability to insure the accuracy of even asimple access count would be of fundamental importance to an Internetservice advertiser, the use of CGI programs to provide even basicaccounting or auditing functions is of limited practical use. Finally,HTML does not provide a tamper-proof way for two URLs to be accessed insequence with just one URL reference button, such as, for example, aserver CGI counter URL reference followed by external server URLreference.

SUMMARY OF THE INVENTION

Thus, a general purpose of the present invention is to provide a systemand method of reliably tracking and redirecting hyper-link references toexternal server systems.

This is achieved by the present invention through the provision of amessage to a tracking server system in response to a client systemreferencing a predetermined resource locator that corresponds to aresource external to the tracking server system. The tracking serversystem indirectly provides for the client system to have aninformational element selectable by the client system, where theinformational element is graphically identified on the client systemwith informational content obtainable from a content server systemthrough use of a content resource locator. The informational elementincludes a tracking resource locator, referencing the tracking serversystem, and data identifying the informational element. The selection ofthe informational element causes the client system to use the trackingresource locator to provide the data to the tracking server system andto use the content resource locator to obtain the informational contentfrom the content server system.

Thus, an advantage of the present invention is that URL reference datais captured in an expedient manner that interposes a minimum latency inreturning the ultimately referenced web page while imposing minimumvisibility of the redirection protocol on client users.

Another advantage of the present invention is that independentinvocations of server external support programs and multiple externaldata references are not required as a consequence of the presentinvention, thereby minimizing the CPU and disk intensive load on the webserver computer system and the resulting latency.

A further advantage of the present invention is that the referenceidentifier and a redirection directive can both be maintained whollywithin the URL specification discretely provided by a client HTMLrequest. Thus, the present invention is superior in both efficiency andmaintenance requirements to a CGI counter, or any method thatincorporates a CGI counter.

Still another advantage of the present invention is that programmodifications necessary to support the protocol of the present inventionare implemented entirely at the server end of a protocol transaction.Client side participation in the transaction is within the existingclient side defined HTML protocol.

A still further advantage of the present invention is that theimplementation of the invention introduces minimum exposure toadditional security breaches due to the closed form of the protocolwhile providing substantial security against inappropriate URL andprotocol references. This is accomplished preferably by the inclusion ofvalidation codes inside the URL specification.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other advantages and features of the present invention willbecome better understood upon consideration of the following detaileddescription of the invention when considered in connection with theaccompanying drawings, in which like reference numerals designate likeparts throughout the figures thereof, and wherein:

FIG. 1 provides a schematic representation of client and server computersystems inter-networked through the Internet;

FIG. 2 provides a block diagram of a server computer system implementingan HTTP daemon (HTTPd) server in accordance with a preferred embodimentof the present invention;

FIG. 3 provides a flow diagram illustrating the process performed by apreferred embodiment of the present invention in receiving andprocessing client URL requests;

FIG. 4 provides a flow diagram illustrating the server side processingof special redirect URLs in accordance with another preferred embodimentof the present invention;

FIG. 5 provides a generalized process representation of client andserver computer systems implementing the alternate processes of thepresent invention;

FIG. 6 is a flow diagram illustrating a server-side process thatprovides for the issuance of a content request message in accordancewith a preferred embodiment of the present invention; and

FIG. 7 is a flow diagram illustrating a client-side process thatprovides for the issuance of a tracking message in accordance with apreferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A typical environment 10 utilizing the Internet for network services isshown in FIG. 1. Client computer system 12 is coupled directly orthrough an Internet service provider (ISP) to the Internet 14. Bylogical reference via a uniform resource locator, a correspondingInternet server system 16, 18 may be accessed. A generally closedhypertext transfer protocol transaction is conducted between a clientbrowser application executing on the client system 12 and an HTTPdserver application executing on the server system 16. In a preferredembodiment of the present invention, the server system 16 represents anInternet Business Service (IBS) that supports or serves web pages thatembed hyper-link references to other HTTPd server systems coupled to theInternet 14 and that are at least logically external to the serversystem 16.

Within this general framework, the present invention enables thetracking of the selection of embedded hyper-link references by clientsystem 12. That is, an embedded hyper-link reference is associated witha graphical banner or other Web page element that is selectable, orclickable, by a user of the client system 12. A banner click on a clientsystem is typically made to obtain information, identified in somefashion by the banner graphic that is of interest to the client systemuser. Tracking is preferably enabled by embedding HTML information inthe Web page served to the client system 12. This information is servedfrom any prearranged HTTPd server system to the client system 12. Theprearrangement is with an IBS to track banner clicks, on Web pagesserved by or on behalf of a designated tracking HTTPd server system,such as system 16, that operates to collect the served page providedtracking information.

The embedded information is, in accord with the present invention,sufficient to enable the client computer system 12 to provide trackinginformation to the HTTPd server system 16. As will be seen, thisinformation is also sufficient, directly or indirectly, to enable theclient computer to request the information associated with the bannergraphic. As will also be seen, there are a number of possibleimplementations of the present invention. These implementations cangenerally be categorized as predominately using either a server-side orclient-side process, as involving proprietary, plug-in, and interpretedcontrol processes, and as using any of a number of specific datatransfer protocols.

The preferred embodiment of the present invention utilizes a server-sideprocess implemented as a proprietary modification to the HTTPd serverapplication executed by the server system 16 and that uses the HTTPredirection directive. Thus, a web page served by an HTTPd serversystem, such as the server system 16 or another server system (notshown) to the client 12 embeds a URL reference to a web page served bythe logically external server system. Selection of this embedded URLthrough the client browser of the client computer system 12 resultsinitially in an HTTP transaction with the server system 16 rather thanthe external server. The information stored in the embedded URL firstserved with the web page to client system 12 is thus provided back tothe server system 16 upon selection of the URL even though the apparenttarget of the URL is the external server system. A redirection responseis then provided by the server system 16 to the client system 12providing the corresponding redirection URL.

As shown in FIG. 2, the server system 16 receives the redirectionrequest information via a network connection 20 to a network interface22 within the server system 16. The network interface 22 is coupledthrough an internal bus 24 to a central processing unit (CPU) 26. TheCPU 26 executes a network operating system 28 in support of the networkinterface 22 and other functional aspects of the server system 16. Thenetwork operating system 28 supports the execution by the CPU 26 of anHTTPd server application 30 that defines the responsive operation of theserver system 16 to HTTP requests received via the network 20. Finally,the network operating system 28 provides for temporary and persistentstorage of data in a mass storage device 32 preferably including apersistent storage media such as provided by a conventional hard diskdrive.

In accordance with the preferred embodiment of the present invention,the embedded redirection information provided as part of a URL HTTPrequest is processed by the HTTPd server 30. Preferably, the processingby the HTTPd server 30 is performed through the execution of the server30 itself as opposed to the execution of any external CGI programs orthe like. The redirection information is processed by the execution ofthe server 30 to identify and validate the particular URL reference thatprovided the redirection information and to generate a redirectiontarget URL.

In a preferred embodiment of the present invention, an embedded URLcontaining redirection information is formatted as follows:

-   -   http://<direct_server>/redirect?<data>?http://<redirect_server>

The direct_server portion of the embedded URL specifies the HTTP servertarget of a transaction that is to be initially established by theclient system 12. The remaining information is provided to the trackingor targeted direct server. The direct server may be any HTTPd serveraccessible by the client system 12 that has been designated to serviceredirection requests in accordance with the present invention.

The term “redirect” in the embedded redirection URL is a key word thatis pre-identified to the HTTPd server 30 to specify that the URLcorresponds to a redirection request in accordance with the presentinvention. Although the term “redirect” is the preferred term, any termor code may be selected provided that the term can be uniquelyidentified by the HTTPd server 30 to designate a redirection URL. Therecognition processing of the “redirect” term is preferably performedthrough the execution of the server 30 by way of a correspondingmodification to the HTTPd server application. That is, the HTTPd serverapplication is modified to recognize the term “redirect” as a key wordand to execute a subprogram to implement the server-side process of thispreferred embodiment. Alternately, the modification to the HTTPd serverapplication can be implemented as a “plug-in” binary program operativethrough a conventional interface provided with the HTTPd serverapplication to obtain essentially the same functionality. Although ofpossibly lesser performance, a server application embedded language,such as Java™ or JavaScript™, may be also alternately used to implementthe server-side process of recognizing the “redirect” key word andperforming the further processing to implement the present invention.

The “data” term of the redirection URL provides reference identifierdata to the HTTPd server 30 that can be used to further identify andpotentially validate a redirection URL to the HTTPd server 30. The datathus permits an accounting of the redirection URL to be made by theHTTPd server 30. In the context of an advertisement, the data may encodea particular advertising client for whom access data may be kept, aparticular instance of the graphic image provided to a client system 12in association with the redirection URL, and potentially a validationcode that may serve to ensure that inappropriate client uses of aredirection URL can be distinguished and discarded by the HTTPd server30.

An exemplary redirection URL, constructed using HTML in accordance witha preferred embodiment of the present invention, is as follows:

<a href=”http://www.infoseek.com/IS/redirect?NwPg-003-   AA?http://www.newspage.com”>

Within the redirection data, the data component “NwPg” serves as aclient or account identifier. The data component “003” is a seriesidentifier indicating a particular graphic image that was associatedwith the redirection URL as embedded in the web page served to theclient system 12. Finally, the data component “AA” may be utilized toprovide a basic validation identifier that serves to permit the HTTPdserver 30 to identify inappropriate repeated submissions of theredirection URL to the server system 16 or those that are determined tobe obsolete by convention.

In an alternate embodiment of the present invention, the validation dataencodes a data representation that can be used in conjunction with theHTTP protocol to provide information regarding the client system 12 thatsubmitted the redirection URL and, optionally, the graphics seriesidentifier data, to limit repeated use of the redirection URL by thesame client system 12 within a defined short period of time. Thus, aninappropriate attempt by a third party client to, in effect, tamper withthe data collected by the server system 16 with respect to anyparticular redirection URL can be identified with relative if notcomplete certainty and blocked. In addition, date codes older than acertain time interval can be declared by computation to be invalid.Consequently, a copy of the embedded redirection URL cannot be stored ona client system 12 and remain viable for use for longer than a period oftime defined exclusively by the server computer system 16.

Each of the data terms within a redirection URL may be statically ordynamically created by the HTTPd server 30 as part of the process oforiginally serving a web page with the embedded redirection URL to aclient computer system 12. With dynamic generation, different graphicimages corresponding to a single advertiser or one of any number ofadvertisers may be effectively served with an otherwise staticallydefined web page. The data terms of the embedded redirection URL may bedynamically selected based on the identity of the advertiser andgraphics image in addition to separately establishing a hypertext linkto the graphics image as part of an instance of serving a particular webpage by the HTTPd server 30. Indeed, the selection of advertiser andgraphics image could be made at least in part on the identity of theclient computer system 12 as established through information provided bythe conventional operation of the HTTP protocol, and on the clientprofile if known.

The validation code may also be dynamically generated. In an alternateembodiment of the present invention, the validation code encodes arepresentation of the day of the year with the account and imageidentifier data terms to generate an identifier, preferably encoded astwo digits, that provides a sufficient degree of uniqueness to allow anembedded redirection URL to be aged on a per day basis. Furthermore, thevalidation code remains constant on a per day basis and thereby stillpermits the number of references on a per day per specific client system12 basis to be tracked by the HTTPd server 30 so as to limit thefrequency that a specific instantiation of the web page is repeatedlypresented to a specific client 12. Additionally, the HTTPd server 30 mayoperate to block operation on a received redirection URL where thecorresponding web page has not recently been served to the requestingclient 12.

Various bit shift, check sum, and modulo arithmetic algorithms can beutilized to generate the validation code in a consistent manner known tothe HTTPd server 30, but that cannot be readily discerned uponexamination of the resulting redirection URL by a specific clientcomputer system 12. Alternately, the validation code may be anarbitrarily selected value that is implicitly recognized as valid by theHTTPd server 30 for a programmable period of time from one day toseveral weeks or longer. In the extreme, and consistent with theinitially preferred embodiment of the present invention, the validationcode is a static value provided as part of the embedded redirection URL.

Independent of the particular manner the validation code is generated orthe assigned length of time that the code is recognized by the HTTPdserver 30 as valid, evaluation of the data terms of a redirection URL ispreferably performed completely internally to the HTTPd server 30. Thedata terms are preferably sufficiently complete as to be unambiguous inidentifying a particular instantiation of an embedded redirection URLwithout significant, if any, resort to the loading and execution of anexternal program or even significantly to interrogate look-up filesstored by the persistent storage device 32. Consequently, the burden ofevaluating a redirection URL in accordance with the present invention isalmost completely computational in nature. As is conventionallyappreciated, the performance of a server computer system 16 is nottypically computationally bound, but rather bound by the rate ofinput/output (I/O) access to the persistent storage device 32 and to thenetwork 20. By substantially if not completely limiting the evaluationof the redirection URL to a computational operation, with only a limitedI/O operation to save auditing or accounting data obtained in connectionwith a redirection URL, an optimally minimal burden on the servercomputer system 16 is realized by the operation of the presentinvention. Indeed, the saving of accounting or auditing data may becached by the network operating system 28 to defer the write I/Ooperation to the persistent storage device 32 until otherwise excess I/Obandwidth is available in the ongoing operation of the server computersystem 16.

The final portion of the preferred structure of a redirection URL is asecond URL. This second URL preferably identifies directly the targetserver system for the redirection. Preferably, any path portion providedas part of the direct server specification of the redirection URL isrepeated as a path component of the redirect server portion of theredirection URL. However, path portion identity is not required. Ingeneral, all that is required in accordance with the present inventionis a one to one correspondence between the direct server and redirectserver terms of the redirection URL. A less strict relationship may beused if the impact upon the auditing or accounting data collected by theoperation of the present invention is consistent with the desiredcharacteristic of that data. For example, different direct serverspecifications may correlate to the use of a common redirect server as ameans of further identifying a particular instantiation of an embeddedredirection URL. Alternately, otherwise identical instantiations of anembedded redirection URL may reference any of a number of redirectservers. Thus, the embedded redirection URL provides only an indirectreference to the ultimately servicing redirect server and relies on thedirect server identified server system or the redirect serversthemselves to resolve the second URL into a direct reference to anultimately servicing redirect server. This may be done to distributeload on the cooperatively operating redirect servers or to provide ameans for verifying the auditing or accounting data collected by theongoing operation of the present invention. Indeed, the second URL of aredirection URL can itself be a redirection URL, though care needs to betaken not to create an infinite redirection loop.

A preferred method 40 of processing redirection URLs provided to aserver computer system 16 by a client computer system 12 is illustratedin FIG. 3. As each client request is received 42 the data provided aspart of the request is examined to determine whether the request embedsthe redirect key word 44. If the URL data does not specify a redirectionrequest consistent with the present invention, the URL data is checked46 to determine whether the URL data conventionally specifies anexistent local web page. If the web page does not exist or, based on theclient identification data provided via the HTTP protocol in connectionwith the URL client request, the particular client is not permittedaccess to the existent web page, the HTTPd server 30 determines acorresponding error message 48 that is returned to the client computersystem 12. Otherwise, the HTTPd server 30 proceeds and serves the localweb page 50 to the client computer system 12.

Where URL data at least specifies a redirection request 52, the URL datais further checked for validity. A table of valid combinations of clientand graphic image identifiers, preferably cached in memory in the serversystem 16, may be used to initially establish the validity of theredirection request. The validation code may either be checked byrecalculation based on the provided redirection data or checked againstanother table of validation codes that are current. In either event, therelative timeliness of the redirection request can be determined fromthe age of the validation code and therefore serve as basis fordetermining whether the current redirection request is timely orsuspect. Furthermore, additional checks may be performed to verify thatthe corresponding web page has indeed been served recently by the servercomputer system 16 to the particular requesting client computer system12 based on a short term log of local web pages actually served by theserver computer system 16. Finally, access permissions enforced by theserver computer system 16 can be checked against the identification ofthe client computer system 12 to categorically limit redirection todefined classes of clients. Where the request is determined to beinvalid for any reason, an appropriate denial message is generated andissued 48.

Where a redirection request is determined valid, any or all of the dataprovided as part of the redirection request or provided to the HTTPdserver 30 through the conventional operation of the HTTP protocol can belogged through the network operating system 28 to the persistent storagedevice 32 for subsequent manipulation, analysis and reporting. Theredirection request is then further processed to obtain the second URLidentifying the target redirection server 56. This second URL is thenspecified in the location field of a redirection message, preferably atemporary redirection message, that is issued 58 back to the clientcomputer system 12 that issued the redirection URL initially.

The process 40 in accordance with a preferred embodiment of the presentinvention, is performed essentially entirely within the HTTPd server 30.The implementation of the process 40 can be performed through amodification and extension of the processing flow implemented by theHTTPd server 30, through a corresponding modification of the serversource code. These modifications and additions may be made utilizingconventional programming techniques.

The redirection capability provided by the present invention is fullyconsistent with existent de-facto standard redirection capabilitiesprovided by conventional HTTPd servers. A further detailed portion 60 ofthe process 40 is shown in FIG. 4. Within the operation of the HTTPdserver 30, the URL data 62 is received and initially parsed 64 toidentify the appropriate existence of the redirect key word. Where thespecific form of the redirection URL of the present invention is notidentified 66, the URL is further processed in a conventional manner todetermine whether any other form of redirection is applicable. Inaddition, an evaluation of conventional access privileges to a local webpage where no conventional redirection is specified can also beperformed with, ultimately, an appropriate response message being issued68.

In the specific instance where the URL request is of the specialredirect form consistent with the present invention, as opposed toconventional HTML redirection capabilities, the URL data is processed 70and, in combination with the HTTP protocol-provided data identifying theclient computer system 12, a database record is created or updated inthe persistent mass storage device 32 at 72. The second URL is thenextracted 74 and a redirection message, specifically a type 302temporary redirection message, is prepared. As before, the second URLmay be a direct or literal URL or an indirect redirection target serveridentification that is resolvable by the HTTPd server 30 into a URL thatis at least sufficient to identify the target redirection server. Sincethe second URL, as embedded in a Web page, is defined throughprearrangement with the operation of the HTTPd server 30, resolution ofany indirect redirection target server identification is fullydeterminable by the HTTPd server 30 through, for example, a databaselook-up operation.

A redirection message including a location field is then created by theHTTPd server 30. This location field is provided with the direct orresolved target redirection server URL. The redirection message is thenissued 58 to the originally requesting client computer system 12.

Other server-side operative embodiments of the present invention can useother specific protocols to transfer the tracking information from theclient system 12 to the HTTPd server 30. These other HTTP protocolmethods include, for example, GET, FORMS, OPTIONS, HEAD, PUT, DELETE,AND TRACE. Use of these other protocol methods are generally similar,differing in their requirements for specific browser support for theprotocol methods and details of their specific HTML markup coding intoWeb pages.

As an example of the use of these other protocol methods, the HTTP GETmethod can be implemented by embedding the following HTML code tags inthe Web pages served to a client computer system.

// HTTP GET <a href =“http://www.infoseek.com/redirect?\ ak =MTCH-2009-1073-GEN&\ rd = http://www.match.com/”> <img src =“http://www.online.com/ads/MTCH1073.gif”> </a>

This HTML code defines “MTCH1073.gif” as the Web page banner graphic,“www.infoseek.com” as the direct URL, “MTCH-2009-1073-GEN” as the data,and “www.match.com” as the target redirection server.

When the above HTML tags are served to the client computer system, aninitial HTTP GET request is issued to “www.online.com” to obtain thebanner graphic. In response to a banner click, a second GET request isdirected to “www.infoseek.com” using the URL:

/redirect?ak=MTCH-2009-1073-GEN&rd=http://www.match.com/

The complete GET request will be of the form:

GET /redirect?ak=MTCH-2009-1073-GEN&\ rd = http://www.match.com/HTTP/1.0User-Agent: Mozilla/3.0 Accept:image/gif, image/jpeg, */*

The HTTPd server 30 records the values of MIME information (such ascookies) and the form variables (in this case ak and rd). An HTTPredirect message is then created by the HTTPd server 30 and returned tothe client computer system. A third and final GET request is then issuedto “www.match.com” in response to the redirection message.

As another example, an HTTP POST method can be used. The Web pageembedded HTML tags can be coded as follows:

// HTTP POST <FORM method = “POST” \ action =“http://www.infoseek.com/redirect”> <INPUT TYPE = hidden\ NAME = “ak” \VALUE = “MTCH-2009-1073-GEN”> <INPUT TYPE = hidden\ NAME = “rd”\ VALUE =“http://www.match.com/”> <INPUT TYPE = image\ SRC =“http://www.online.com/ads/MTCH1073.gif”> </FORM>

This HTML code will result in a GET request being issued automaticallyto “www.online.com” to retrieve the banner graphic. A banner click willresult in a HTTP POST request being sent to “www.infoseek.com” alongwith the FORM NAME and VALUE data. In this case, the data is not encodedinto the URL, but rather is encoded in the body of the POST requestitself. In this example, the POST request will have the form:

POST /redirect HTTP/1.0 User-Agent: Mozilla/3.0 Accept: image/gif,image/jpeg, */* Content-type: application/x-www-form-urlencodedContent-length: 54 ak=MTCH-2009-1073-GEN&rd=http://www.match.com/

When the returned redirection message is received, another GET requestis issued by the client computer system to the redirection targetserver, which is again “www.match.com.”

In accordance with the present invention, a client-side process can alsobe utilized to transparently provide notification of the selection of aWeb page element by a client computer system. FIG. 5 provides arepresentation 78 of the data transfer flows involved in both theserver-side and client-side processes that implement the presentinvention. Common to both server-side and client-side processimplementations, a client computer system 80 issues an initial Web pagerequest over the Internet (not shown) to a Web page server system 82. Acorresponding Web page 84 including a Web page element 86 is returned tothe client computer system 80.

Again, common to both server-side and client-side processimplementations of the present invention the Web page element 86 isprovided through the embedding of information in the Web page 84. In thecircumstance of a server-side process as generally depicted in FIG. 6,the process of the present invention following from a banner click 96results in a client browser action. Specifically, the embeddedinformation controls the operation of the Web browser on the clientcomputer system sufficient to issue a notification URL 98 directed tothe redirection target server system 88, as shown in FIG. 5. The serverprocess 100 initiated in response to the notification URL receiptproduces the redirection message that is returned to the client computersystem 80. In connection with the generation of the redirection message,the server system 88 also logs and optionally processes the datareceived as part of the notification URL 98.

Based on the redirection message, the client computer system 80 thenpreferably issues an HTTP request 102 based on the information containedin the redirection message. Referring again to FIG. 5, the HTTP request102 is provided via the Internet 14 to another Web page server system 90that responds in a conventional manner by the serving of Web page 92 tothe client computer system 80 as the Web page 104 that was inferentiallyreferenced by the Web page element 86.

The method of the present invention utilizing a client-side process isgenerally shown if FIG. 7. The method 106, for the purposes ofexplanation here, generally begins in response to a banner click 108 toinitiate a client process 110 executing in connection with the operationof the Web browser on the client computer system 80. In a preferredembodiment of the present invention, the client process 110 is providedwith the Web page 84 to the client computer system 80. The clientprocess 110 is invoked in response to the banner click and operates tofirst issue a notification URL message 112 and, second, to issue an HTTPrequest 114. Both messages are issued through the Internet 14 and to thetarget server system 88 and Web page server 90, respectively. The orderthat the client process 110 issues the notification URL 112 and HTTPrequest 114 is not significant. Further, acknowledgment of the receiptof the notification URL from the target server system 88 is not requiredprior to issuing the HTTP request 114. Indeed, as evident to the user ofthe client computer system 80, the only response recognized assignificant is the receipt 116 of the Web page 92.

As in the case of the server-side process, the client-side process 110can be implemented in a number of different manners that, for purposesof the present invention, each result in the delivery of data to thetarget server system 88 and a URL request to a Web page server system 90to provide a Web page 92 having a prearranged correspondence with theWeb page element 86. Specifically, the client-side process can bedirectly coded into the browser application or supplied as a browserplug-in to a conventional browser application. The client-side processcan also be implemented through use of Java and JavaScript type applets.

An exemplary client-side process is implemented through the use of aJava Applet. The HTML code that is embedded in the Web page 84, forpurposes of this example, is as follows:

<applet name = “ad” code = “ad.class” width = 468 height = 60> <paramname = img value = “ad.gif”> <param name = notifyurl value =“?MTCH-2009-1073-GEN”> <param name = pageurl value =“http://catalog.online.com/”> </applet>

where the three applet parameters are defined as follows:

“img”—the URI reference to a graphic banner advertisement

“notifyurl”—the “notification” URL holding the accounting data

“pageurl”—the “redirection” URL to use

The applet source is as follows:

import java.applet.Applet; import java.awt.Image; importjava.awt.Graphics; import java.net.URL; importjava.net.MalformedURLException; import java.io.IOException; public classad extends Applet { Image image; URL notifyurl; URL pageurl; public voidint( ) { image = getImage(getDocumentBase( ), getParameter(“img”)); try{ logurl = new URL(getDocumentBase( ), getParameter(“notifyurl”));pageurl = new URL(getDocumentBase( ), getParameter(“pageurl”)); } catch(MalformedURLExeception e) { } } public bold paint(Graphics g) {g.drawImage(image, 0, 0, this); } public booleanmouseDown(java.awt.Event evt, int x, int y) { try { logurl.openStream().close( ); } catch (java.io.IOexception e) { } getApplet Context().showDocument(pageurl); return true; } }

The above example uses two HTTP requests to first issue the “notifyurl”message and, second, to issue the “pageurl” message. Various otherprotocols, however, can be used in connection with the presentinvention. For example, the Java applet can be modified to provide thenotification data to the target server system 88 through use of a TCPconnection. An exemplary implementation of an applet utilizing a TCPconnection is provided below. The applet takes four parameters:

“img”—the URL of the ad image to show

“port”—the TCP port number to use on the target server

“data”—the accounting data to send to the target server

“pageurl”—the “redirection” URL to use

The applet source is as follows:

import java.applet.Applet; import java.awt.Graphics; importjava.awt.Image; import java.io.IOException; import java.io.OutputStream;import java.io.PrintStream; import java.lang.Integer; importjava.lang.String; import java.net.MalformedURLException; importjava.net.Socket; import java.net.URL; public class ad extends Applet {Image image; String host.data; int port; URl url; public void int( ) {image = getImage(getDocumentBase( ), getParameter(“img”)); host =getDocumentBase( ).gethost( ); port =Integer.parseInt(getParameter(“port”)); data = getParameter(“data”); try{url = new URL(getDocumentBase( ), getParameter(“pageurl”));} catch(MalformedURLException e) { } } public void paint(Graphics g) {g.drawImage(image, 0, 0, this); } public booleanmouseDown(java.awt.Event evt, int x, int y) { try { Socket socket = newSocket(host,port); PrintStream ps = newPrintStream(socket.getOutputStream( )); ps.print(data); ps.close( ); }catch (java.io.IOException e) { } getAppletContext( ).showDocument(url);return true; } }

Finally, the above applet can be referenced for execution by embeddingthe following HTML code into the Web page 84.

<applet name=“ad” code=“ad.class” width=468 height=60> <param name=imgvalue=“ad gif”> <param name=port value=“21”> <param name=datavalue=“MTCH-2009-1073-GEN”> <param name=urlvalue=“http://catalog.online.com/”> </applet>

Thus, a comprehensive system and method for accounting or auditingaccesses made by client computer systems to external hyper-linkedservers has been described. The auditing capabilities of this systemprocess impose optimally minimal overhead burden on the redirectionserver system while permitting the data that is gathered to be validatedand reasonably assured to correspond to bona fide accesses to aredirection target server system.

While the invention has been particularly shown and described withreference to preferred embodiments thereof it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

The invention claimed is:
 1. A method comprising: serving, by a firstserver, a web page element on a client computer having an identity for aselection by a user of said client computer, said web page elementincluding an embedded uniform resource locator, said embedded uniformresource locator identifying a first server and including a redirectionuniform resource locator identifying a second server; receiving, by saidfirst server identified in said embedded uniform resource locator, aservice request from said client computer based on said selection ofsaid web page element by said user, in response to said serving of saidweb page element, the request including an identification of said secondserver; redirecting, by said first server, said client computer to saidsecond server identified in said redirection uniform resource locator,in response to said receiving said service request; and tracking, bysaid first server, a frequency of redirecting of client computers tosaid second server by including said redirecting of said client computerto said second server in said frequency.
 2. The method of claim 1,wherein said embedded uniform resource locator further includes saididentity of said client computer.
 3. The method of claim 1, wherein saidservice request includes said identity of said client computer.
 4. Amethod of operating a client computer having an identity, the methodcomprising: receiving a web page element from a first server, said webpage element including an embedded uniform resource locator, saidembedded uniform resource locator identifying said first server andincluding a redirection uniform resource locator identifying a secondserver; presenting said web page element to a user of said clientcomputer for a selection by said user of said client computer; receivingsaid selection of said web page element from said user of said clientcomputer; making a service request to said first server identified insaid embedded uniform resource locator, in response to said receiving ofsaid selection of said web page element by said user, the requestincluding an identification of said second server; and receiving aredirect, from said first server, redirecting said client computer tosaid second server identified in said redirection uniform resourcelocator, in response to said making said service request.
 5. The methodof claim 4, wherein said embedded uniform resource locator furtherincludes said identity of said client computer.
 6. The method of claim4, wherein said service request includes said identity of said clientcomputer.
 7. A server comprising: a CPU configured to: serve a web pageelement on a client computer having an identity for a selection by auser of said client computer, said web page element including anembedded uniform resource locator, said embedded uniform resourcelocator identifying said server and including a redirection uniformresource locator identifying a second server; receive, by said serveridentified in said embedded uniform resource locator, a service requestfrom said client computer based on said selection of said web pageelement by said user, in response to said serving of said web pageelement, the request including an identification of said second server;redirect said client computer to said second server identified in saidredirection uniform resource locator, in response to said receiving saidservice request; track a frequency of redirecting of client computers tosaid second server by including said redirecting of said client computerto said second server in said frequency.
 8. The server of claim 7,wherein said embedded uniform resource locator further includes saididentity of said client computer.
 9. The server of claim 7, wherein saidservice request includes said identity of said client computer.